Honda BF50D overheat at idle

[ArranP]

Works fine at higher RPMs and WOT.

Does this engine have a poppet valve ? if not this I guess the only other thing it could be is the impeller.

Thanks for feedback.

Regards
Arran.

 

[jgmo]

Hi Arran,
If by poppet valve, you mean thermostat then yes, it does have a thermostat. See item 8 in the link below:

https://www.boats.net/catalog/honda/outboard/2007-and-later/50hp/bf50d-xrta-vin-bbej-1000001-to-bbej-1099999/cylinder-block

And, while the thermostat might be partially to blame for an at idle overheat, like you have already suggested, I would also be suspicious of the pump impeller for this. The increased rpm seemingly making the engine temperature go lower does point to a problem with the pump

But, if it were me, I would check both and service as needed. Because, there's a high probability of the cooling system needing some "wholeistic" cleaning and maintenance.

These are very nice outboards so you don't want cooling problems getting too far out of hand.

Good luck.

 

[racerone]

Outboards should get a new impeller about every 5 years.

 

[William01]

If you don’t know the history of the engine I’d suggest you consider changing the entire water pump assembly. If you know for certain that the water pump has never been run dry then you should be good with an impeller and new key. Examine the parts closely and post pictures if in doubt, both the above posters will be able to give you an honest opinion of the condition of the water pump.